This disclosure pertains to wheel extension and steering apparatus, particularly useful for aerial work platform machines such as articulated and telescopic boom lifts which raise a work platform to desired elevation. The apparatus comprises a chassis and chassis support legs pivotally connected to the chassis to position steerable wheels at the ends of the chassis support legs whereby the wheels may be moved between transport positions close to the chassis and working positions at greater distance from the chassis to provide vehicle stability. In apparatus of this type, linear actuators, usually hydraulic, for steering the wheels are aligned generally transverse to the longitudinal axis of the vehicle since they must overcome considerable moment resistance as the extremes of steering angle are approached. Orientation of the linear actuators transversely to the longitudinal axis of the vehicle necessarily exposes the full length of the steering actuators to damage during movement of the vehicle.